Pressure adjusting means for fuel injection nozzles

ABSTRACT

A fuel injection nozzle assembly comprising an elongated holder, a nozzle mounted at one axial end of the holder, a valve element mounted in an axial bore in the nozzle, means defining a spring chamber in said nozzle assembly for mounting therein a compression spring normally biasing the valve element to a closed position, pressure-adjusting means for said spring for selectively regulating the pressure at which the valve opens comprising an adjusting screw member mounted in a threaded axial bore in the holder engaging one end of said compression spring and a locking screw member engaging in a threaded opening extending transversely of said threaded axial bore adapted to engage said adjusting screw to lock the same in a predetermined adjusted position.

United States Patent [72] Inventor Walter J. Gewinner Springfield, Mass. [21] Appl. No. 739,878 [22] Filed June 25, 1968 [45] Patented Mar. 2, 1971 [73] Assignee Ambac Industries, Inc.

Springfield, Mass.

[ 54] PRESSURE ADJUSTING MEANS FOR FUEL INJECTION NOZZLES 5 Claims, 3 Drawing Figs. [52] US. Cl. 239/533, 239/89, 239/453 [51] Int. Cl B05b 1/30 [50] Field of Search 239/533, 453, 96, 95, 94, 93, 92, 91, 90, 89 [56] References Cited FOREIGN PATENTS 405,731 2/1934 Great Britain 239/89 671,940 5/1952 Great Britain 239/89 Primary Examiner-Lloyd L. King Assistant Examiner-Thomas C. Culp, Jr. Attorney-l-Iowson and Howson ABSTRACT: A fuel injection nozzle assembly comprising an elongated holder, a nozzle mounted at one axial end of the holder, a valve element mounted in an axial bore in the nozzle, means .defining a spring chamber in said nozzle assembly for mounting therein a compression spring normally biasing the valve element to a closed position, pressure-adjusting means for said spring for selectively regulating the pressure at which the valve opens comprising an adjusting screw member mounted in a threaded axial bore in the holder engaging one end of said compression spring and a locking screw member engaging in athreaded opening extending transversely of said threaded axial bore adapted to engage said adjusting screw to lock the same in a predetermined adjusted position.

PATENTED m 2 ml INVENTOR. WALTER J. GEWINNER ATT Y3.

PRESSURE ADJUSTING MEANS FOR FUEL INJECTION NOZZLIES This invention relates to improvement in fuel injection nozzles.

The present invention applies generally to the type of nozzle which includes an elongated nozzle holder, and a fuel injection nozzle supported at one axial end of the holder by means of a capnut. The terminal end of the nozzle holder confronting the nozzle is usually provided with an enlarged opening defining a spring chamber within which is mounted a compression spring which bears against a spring seat at its inner terminal end. The spring seat engages the valve element to normally bias it to a closed position wherein the valve tip is seated tightly against the valve seat. The assembly further includes the aligned passages in the holder and nozzle for delivering fuel under pressure to the nozzle and a passageway communicating with the spring chamber for venting leakage fuel back to the fuel supply, or in some instances, into the engine combustion chamber. The holder and. nozzle are maintained in Y predetermined aligned relation by means of a locating pin.

In these assemblies it is necessary to adjust the bias of the spring thereby to determine the fuel pressure at which the valve opens. In prior assemblies this was done by means of a plurality of shims disposed in the spring chamber engaging the upper terminal end of the compression spring. Adjustment of the valve for the desired compression was by trial and error and consisted in varying the number and size of the shims. The disadvantage of compression adjustment by this method is that after each change in the shim arrangement, the nozzle assembly has to be completely assembled and then after adding or removing shims of various thicknesses, the components are reassembled, the capnut tightened to correct torque, and the valve opening pressure rechecked hydraulically. This procedure is time consuming, and presents the possibility of introducing dirt or foreign matter to the assembly which may cause malfunction of the nozzle and there is the possibility of damaging parts thereof such as shearing the locating pin with repeated loosening and tightening of the capnut.

The present invention eliminates the disadvantage and the drawbacks of prior assemblies and provides a comparatively simplified means for adjusting the compression spring. The arrangement consists simply of a pressure adjusting screw mounted in a threaded bore in the upper end of the spring chamber selectively adjustable axially to vary the compression of the spring and a threaded setscrew in a threaded bore extending transversely to the bore in the upper end of the spring chamber, the setscrew having a conical tip which engages a beveled peripherally extending shoulder on the pressure adjusting screw. This arrangement serves to jam both the threads of the adjusting screw as well as the setscrew to produce a double locking action. In view of the above, it is clear that the present invention provides a new and improved means for adjusting the compression spring of a fuel injection nozzle assembly. In accordance with the present invention, the compression may be adjusted easily and very accurately without disassembling major parts of the assembly. Accordingly, the procedure is less time consuming and the possibility of introducing dirt or foreign matter is obviated. Furthermore, since it is not necessary to disassemble parts, there is no danger of shearing the locating pin as was the case in prior assemblies.

These and other objects of the present invention are hereinafter more fully set forth and described with reference to the accompanying drawing, wherein:

FIG. I is a transverse sectional view of a fuel injection nozzle assembly incorporating spring pressure-adjusting means in accordance with the present invention;

FIG. 2 is a sectional view taken on lines 2-2 of FIG. I; and

FIG. 3 is an enlarged sectional view taken on lines 3-3 of FIG. 2.

Referring now to the drawing and particularly to FIG. 1 thereof, there is illustrated a fuel injection nozzle assembly generally designated by numeral 10 incorporating compression spring adjustment means in accordance with the present invention. The assembly includes an elongated generally cylindrical holder 12 and a nozzle 14 mounted at one axial end of the holder 12 by means of the capnut 16. The holder includes a passage 18 through which fuel from a suitable supply source is delivered to the nozzle 14.

As illustrated, the nozzle includes a generally cylindrical body portion 20 and a shank 22 of reduced cross section projecting from one end of the body portion, the nozzle having an axial bore 24 therein within which is mounted a valve element 26. In the present instance a disclike spacer 30 is mounted between the lower axial end face of the holder and the upper axial end face of the nozzle and a locating pin 32 is provided to align a nozzle in a predetermined position relative to the holder so that fuel from the passage 18 is directed to the angled passageway 34 in the nozzle and thence to the enlarged portion of the axial bore 24 defining the fuel chamber F.

In the present instance a tip insert 40 is mounted in the outer axial end of the shank 22 of the nozzle and is of a contoured internal configuration defining a conical valve seat 412 against which the complementary tapered tip portion 44 of the valve seats in the normally; closed position of the valve.

The valve is normally biased to a closed position by means of a compression spring housed in a spring chamber S formed in the lower end of the holder. The compression spring 50 at its lower end engages on a spring seat 52 which in turn bears against a pin projection 26a of the valve 26. A doughnutlike spacer 54 is-abutted by the opposite end of the compression spring 50.

In accordance with the present invention, a new and improved means is provided for selectively adjusting the compression of the spring 50. To this end, there is provided an adjusting screw 60 which is threaded in a bore 62 of reduced cross section at the upper end of the spring chamber. This adjusting screw has a hexagonal recess 64 at opposite axial ends thereof to permit adjustment thereof in the bore 62 by means of a ball end screwdriver. Access to the adjusting screw for adjustment and also for initial assembly thereof is through a pieshaped cutout 70 in the wall of the holder 12. As illustrated, the adjusting screw has an axially extending opening 72 running the length thereof to permit any fuel leakage into the spring chamber to be vented through the adjusting screw and back to the main fuel supply or to another location, if desired, such as the engine intake. Further, as illustrated, the adjusting screw has circumferentially extending exterior beveled edges 76 and 78. In the present instance the adjusting screw 60 may be locked in a predetermined adjusted position by means of a setscrew 80 mounted in a threaded opening 82 extending transversely to the threaded bore 62. The setscrew 80 has a conical head 84 adapted to engage the upper beveled edge 76 of the adjusting screw and securely lock it in position. By this arrangement both the threads of the adjusting screw as well as the setscrew are jammed to produce a double-locking action. Further, by reason of the beveled head'84 of the setscrew and the conical edge of the adjusting screw, a substantial range of adjusting screw positions can be accommodated.

Accordingly, in adjusting the compression of spring 50 employing adjusting means in accordance with the present invention, all of the parts of the holder and nozzle may be completely assembled and with the setscrew in a retracted position, the adjusting screw may be threaded inwardly or outwardly to a predetermined setting for compression of the spring 50. When a desired position has been attained, conical head 84 wedges against the beveled edge 76. As noted above, this produces the double locking action by reason of the jamming of the threads of the adjusting screw and the setscrew MI. The assembly is now ready for checking the valve opening by pressurizing the assembly hydraulically.

While a particular embodiment of the present invention has been illustrated and described herein, it is not intended to limit the invention, and changes and modifications may be made therein within the scope of the following claims.

lclaim:

1. A fuel nozzle assembly comprising an elongated holder, a nozzle mounted at one axial end of said holder, a valve element mounted in an axial bore in said noule, means defining a spring chamber in said nozzle assembly for mounting therein a compression spring assembly in direct engagement with said valve element to normally bias said valve element to a closed position, pressure-adjusting means for said spring assembly for selectively regulating the pressure at which said valve opens consisting of an adjusting screw member mounted in a threaded axial bore in the holder directly engaging one end of said compression spring assembly and a locking screw member engaging in a threaded opening extending transversely of said threaded axial bore adapted to engage a beveled outer circumferentially extending edge of said adjusting screw member to lock the same in a predetermined adjusted position, said adjusting screw member being hollow and said holder having an opening in said sidewall for access to said adjusting screw member and for venting leakage fuel from said spring chamber.

2. A fuel injection nozzle assembly as claimed in claim 1 wherein said spring chamber extends from said one axial end of the holder.

3. A fuel injection nozzle assembly as claimed in claim 1 wherein said locking screw member has a conical tip adapted to engage a beveled edge of said adjusting screw member.

4. A fuel injection nozzle assembly as claimed in claim 1 wherein said compression spring assembly includes a compression spring and upper and lower spring seats at opposite axial ends of said spring engaging the adjusting screw member and valve element respectively.

5. A fuel injection nozzle assembly as claimed in claim 1 wherein said adjusting screw member has hexagonal-shaped recesses at opposite axial ends to permit adjustment thereof by means of a ball end screw driver. 

1. A fuel nozzle assembly comprising an elongated holder, a nozzle mounted at one axial end of said holder, a valve element mounted in an axial bore in said nozzle, means defining a spring chamber in said nozzle assembly for mounting therein a compression spring assembly in direct engagement with said valve element to normally bias said valve element to a closed position, pressure-adjusting means for said spring assembly for selectively regulating the pressure at which said valve opens consisting of an adjusting screw member mounted in a threaded axial bore in the holder directly engaging one end of said compression spring assembly and a locking screw member engaging in a threaded opening extending transversely of said threaded axial bore adapted to engage a beveled outer circumferentially extending edge of said adjusting screw member to lock the same in a predetermined adjusted position, said adjusting screw member being hollow and said holder having an opening in said sidewall for access to said adjusting screw member and for venting leakage fuel from said spring chamber.
 2. A fuel injection nozzle assembly as claimed in claim 1 wherein said spring chamber extends from said one axial end of the holder.
 3. A fuel injection nozzle assembly as claimed in claim 1 wherein said locking screw member has a conical tip adapted to engage a beveled edge of said adjusting screw member.
 4. A fuel injection nozzle assembly as claimed in claim 1 wherein said compression spring assembly includes a compression spring and upper and lower spring seats at opposite axial ends of said spring engaging the adjusting screw member and valve element respectively.
 5. A fuel injection nozzle assembly as claimed in claim 1 wherein said adjusting screw member has hexagonal-shaped recesses at opposite axial ends to permit adjustment thereof by means of a ball end screw driver. 